COPENHAGEN, March 8 (Reuters) - Danish inventor Peter Madsen denies murdering Swedish journalist Kim Wall aboard his homebuilt submarine in August but admits indecent handling of a corpse, his defence lawyer said at the opening of his trial in Copenhagen on Thursday.

Wall, a 30-year-old freelance journalist who was researching a story on the entrepreneur and aerospace engineer, went missing after Madsen took her out to sea in his 17-metre (56-foot) submarine in August last year.

Later that month, police identified a headless female torso washed ashore in Copenhagen as Wall's.

"The accused denies voluntary manslaughter, but admits violating the law about indecent handling of a corpse," his lawyer Betina Hald Engmark said in court. Under the Danish penal code, manslaughter is used to describe the deliberate killing of a person and there is no distinction between manslaughter and murder. Involuntary manslaughter is used when the killing is not intentional.

Madsen is charged with murdering and dismembering Wall, along with a charge of sexual assault without intercourse of a particularly dangerous nature.

He has admitted dismembering her body on board his submarine and dumping her body parts in the sea.

"He maintains that she died as a consequence of an accident," Hald Engmark told TV2 News before entering the court.

The cause of her death is yet to be determined, but the prosecutors said she died by strangulation or cutting of her throat. (Reporting by Emil Gjerding Nielson, Editing by William Maclean)